A case of immunoglobulin g4-related disease presenting as a pleural mass.

Immunoglobulin G4 (IgG4)-related disease is a newly recognized condition characterized by fibroinflammatory lesions with dense lymphoplasmacytic infiltration, storiform-type fibrosis and obliterative phlebitis. The pathogenesis is not fully understood but multiple immune-mediated mechanisms are believed to contribute. This rare disease can involve various organs and pleural involvement is even rarer.